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Yet Another Poweramp
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So, what is YAP?
YAP is a project born in a spring night of 2008, while listening to the PGP amp and trying to draw the conclusions about the PGP construction oddysey. It was indeed a difficult and expensive construction and, unfortunately, based on the feedback that I got so far, not a plug and play project. Starting with trimming the error correction power stage and ending up with the final wiring tuning requires not only lots of work but also specialized equipment, not available in each DIYer lab.
Another lesson learned was about the PGP PCB's. Someone compared the front end PCB complexity to a PC motherboard... It is indeed very complex, while for cost savings reason I never generated the solder mask and silk screen layers. This is probably one of the reason why I was told that in particular the front end is almost impossible to debug. An error (wrong resistor value, or pin swapped tranny) and you'd better start from scratch rather then starting to guess where the problem lies.
One to another, some legitimate question arised:
Q1: To achieve similar performance, is the PGP complexity really required?
Q2: Is it possible to use local negative feedback to replace the error correction mechanism?
Q3: Are IC's good in a high performance design?
Q4: Why was the PGP performance (in 4ohm) speakers subjectively poor?
Q5: How far can we push the open loop gain(s) performance without moving to another technology (SMD)?
...and many more that you will, hopefully, find answers in these pages.
Another way to skin the cat